NYSDEC Region 1 Freshwater Fisheries I FISH NY Program Food Web & Bioaccumulation th th Grade Level(s): 6 – 8 NYS Learning Standards Time: 35-45 minutes Core Curriculum MST Group Size: 20-30 students Living Environment: Standard 4 Students will: understand and apply scientific concepts, principles, and Summary theories pertaining to the physical Students will be introduced to some of the setting and living environment and animals that live in an aquatic environment. The recognize the historical development dynamics of food chains and food webs, and the of ideas in science. roles organisms play as consumers, producers, and • Key Idea 5: Organisms maintain a decomposers in the food pyramid will be dynamic equilibrium that sustains introduced. Students will participate in an activity life. to learn how aquatic organisms and humans play a • Key Idea 6: Plants and animals role in the aquatic food web as consumers. depend on each other and their physical environment. Objectives • Key Idea 7: Human decisions and The lesson objective is to create an activities have a profound impact understanding of the dynamics of a food web, on the physical and living chain, and pyramid in aquatic environments, and environment. how humans can play an important role in the health of food webs. Other goals include understanding biotic (living) and abiotic (non-living) environmental factors, fish behavior, and bioaccumulation. After this presentation, students will be able to: • Explain the parts of a food pyramid and some of the inter-relationships within a food web and food chain. • Identify different organisms found in an aquatic ecosystem. • Classify the feeding roles of different organisms found in an aquatic ecosystem. • Discuss human impacts on the environment and possible solutions. • Explain how bioaccumulation affects an ecosystem Materials • Fish mounts or pictures • Freshwater and/or Saltwater Life Cards • Poker chips (at least 3 different colors; 1 color 30% of total number) • Small plastic, paper, cloth bags or containers • Large area (clear of desks) • Chalk or dry erase board and markers • Food Web worksheet NYSDEC Region 1 Freshwater Fisheries 2013 [email protected] 631.444.0283 Page 1 NYSDEC Region 1 Freshwater Fisheries I FISH NY Program Vocabulary • Abiotic Factors – the non-living aspects of the environment; ex: water, sunlight, rocks, oxygen, wind, temperature • Bioaccumulation – the progressive increase in the amount of a chemical or substance in an organism • Biotic Factors – the living aspects of the environment; ex: plants and animals • Carnivores – are meat eaters; feed solely on other consumers • Consumers - cannot perform photosynthesis; use organic substrates to get energy; ex: herbivores and carnivores • Decomposers - consume dead organisms; ex: bacteria, some insects, and fungi • Detritus – dead or decaying plant and animal matter; food for some consumers • Ecosystem – a community of organisms and their environment • Eutrophication – the process where water bodies receive extra nutrients that cause an increase in plant growth • Food Chain - the transfer of food energy from plants through herbivores to carnivores; ex: plant-insect-fish-seal; phytoplankton-zooplankton-fish-osprey; algae-clam-human • Food Pyramid – the flow of energy up through food chain (trophic levels), from producers through primary, secondary, tertiary and quaternary consumers • Food Web – are food chains linked to form a complex interconnected web • Herbivores – are primary consumers; feed solely on plants • Omnivores - feed on both plants and animals • Photic Zone – the sunlit portion of the water • Phytoplankton – are tiny free-floating aquatic plants that drift with ocean currents • Producers – are the base of food pyramid; able to produce oxygen through photosynthesis; ex: plants • Trophic Level - is the level or position of an organism in a food chain • Zooplankton – are tiny free-floating aquatic animals that drift with ocean currents, and feed on phytoplankton Vocabulary words will show up once in bold Background Every living organism needs energy to survive. The source of energy for most life on earth is the sun. Green plants can use the energy of the sun to make their own food through photosynthesis. Because green plants produce their own food, they are called producers. All other organisms get their food energy by consuming other organisms and are thus called consumers. Every organism can be classified by where it fits into the food pyramid. Most broadly, all organisms fit into one of three trophic levels: producers, consumers, and decomposers; depending on how it gets its energy. Every living organism needs energy to survive. Organisms NYSDEC Region 1 Freshwater Fisheries 2013 [email protected] 631.444.0283 Page 2 NYSDEC Region 1 Freshwater Fisheries I FISH NY Program within a community depend on one another for food to create energy for survival. This feeding relationship is referred to as a food chain. A food chain is a linear arrangement of organisms up through trophic levels expressing how each receives its energy, either by making its own energy (plants) or by consuming other organisms. Food Chain example Human Sun Algae Bass Sunfish Clams Living and Non-Living Factors Biotic (Living) Factors Food Pyramid The living factors in an environment are called biotic factors. Trophic levels, or the feeding levels within a food pyramid, begin with Quaternary producers at the base, which produce their own food through photosynthesis. This group contains the greatest amount of energy Tertiary within a food web or chain. At the top of food pyramid, one will Consumers find a limited number of top predators, mainly due to a much Secondary smaller amount of energy to be found and shared. The consumers are those organisms that cannot make their own Primary food, and therefore must eat producers or other consumers to gain energy. Primary consumers, which are herbivores, Producers feed solely on plants (producers). The secondary consumers are carnivores and omnivores. Feeding on the secondary consumers are tertiary (third level) consumers, then quaternary (fourth level) and so on to the top predators of an ecosystem. Examples of top predators are sharks, osprey, and humans. Omnivores eat both plants and animals, carnivores eat only meat, and decomposers are those organisms that consume dead plant and animal material called detritus. Decomposers are not scavengers, as scavengers are considered carnivores that eat parts of dead animals. Decomposers are recyclers. It takes an entire spectrum of organisms to decompose a large dead animal, from a scavenging raccoon to a chipmunk, to maggots, to bacteria that feed on the skin. Without them, nutrients would not cycle back into the environment, therefore making it impossible for other organisms to sustain life. NYSDEC Region 1 Freshwater Fisheries 2013 [email protected] 631.444.0283 Page 3 NYSDEC Region 1 Freshwater Fisheries I FISH NY Program Abiotic (Non-Living) Factors Although, not often included in the food web, abiotic factors or the non-living aspects (water, sunlight, temperature, etc.) play an important role. Climate will decide which food resources, and how much water and sunlight are available to organisms in any given ecosystem. Water and sunlight are necessary for plant growth and photosynthesis, and also provide animals with the basic needs of survival. Food Web In every environment and ecosystem there are different food webs. Although the organisms may be different, the food pyramid order of producers, primary consumers, secondary consumers, tertiary consumers, and so forth on up, is always the same. For the purpose of this lesson, we will focus on aquatic food webs, both saltwater and freshwater. Within an ecosystem, there are many interconnected food chains which create a diverse and strong food web. For instance, at low tide the terrestrial raccoon may feed on an aquatic animal like a blue crab or mussel. Saltwater Micro-organisms known as plankton are key players in the food web of a marine environment. Occupying the Food webs are a diverse combination of photic zone or sun-lit portion of the water are two types food chains linked to form a complex of plankton, phyto and zooplankton. Phytoplankton or interconnected web. plant plankton account for 95% of the primary productivity in the ocean. Zooplankton or animal plankton eats phytoplankton, and thus a primary consumer. Moreover, larger zooplankton eat smaller zooplankton; small bait fish eat larger zooplankton; and large predatory fishes eat the small bait fish. This series of feeding relationships makes up the marine food chain. When you factor in other species that feed on the same organism, then the chain becomes a web. Freshwater At the base of the freshwater food web are again the producers, such as phytoplankton, algae, duckweed, and lily pads. Just like on land, plants in water undergo photosynthesis and provide aquatic organisms with oxygen. Freshwater primary consumers include zooplankton and invertebrates. Smaller fish that consume the invertebrates are secondary consumers. Predators at the top level include largemouth bass, smallmouth bass, walleye, chain pickerel, and perch. Humans and carnivorous birds like the osprey or eagle are also part of the freshwater food chain. NYSDEC Region 1 Freshwater Fisheries 2013 [email protected] 631.444.0283 Page 4 NYSDEC Region 1 Freshwater Fisheries I FISH NY Program Human Impacts & Bioaccumulation In many food webs, humans can be the top predator and are responsible for the decline in population, or in some cases endangering many species. Overfishing, introduction of non-native species, eutrophication, and bioaccumulation of toxic chemicals and substances are just a few examples of how humans impact aquatic food webs. Humans can negatively impact aquatic food webs in many ways by overfishing, introducing non-native species, or polluting an aquatic ecosystem. For example, in a saltwater ecosystem, clams may filter out pollutants in the water such as heavy metals, coliform bacteria from sewage contamination, or oil washed off the land. When pollutant levels are high, they build up inside of the clams, concentrating the toxic substances.